Pusher centrifuge with two or more drums

ABSTRACT

IN A PUSHER CENTRIFUGE FOR MATERIAL TO BE CENTRIFUGED, HAVING TWO OR MORE CENTRIFUGING DRUMS THROUGH WHICH SAID MATERIAL BEING CENTRIFUGED PASSES SUCCESSIVELY, MEMBER FOR FEEDING SAID MATERIAL TO BE CENTRIFUGED TO THE INLET SIDE OF THE-IN THE DIRECTION OF THE PASSING MATERIAL-FIRST OF SAID DRUMS, AND FOR EACH OF SAID DRUMS A PUSH MEMBER ASSOCIATED WITH THE INLET SIDE OF THE DRUM, THE IMPROVEMENT THAT THERE IS PROVIDED FOR AT LEAST ONE FURTHER OF SAID DRUMS ANOTHER FEED MEMBER SUPPLYING MATERIAL TO BE CENTRIFUGED TO THE INLET SIDE OF SAID FURTHER DRUM.

June 15, 1971 4 E, RUEGG PUSHER CENTRIFUGE WITH TWO OR MORE DRUMS Filed Oct. 17, 1969 INVL'NTOR. Ernst R U'BCJCJ Attor eys United States Patent Oifice 3,585,132 PUSHER CENTRIFUGE WITH TWO OR MORE DRUMS Ernst Riiegg, Kusnacht, Switzerland, assignor to Escher Wyss Limited, Zurich, Switzerland Filed Oct. 17, 1969, Ser. No. 867,212 Claims priority, application Switzerland, Oct. 30, 1968, 16,160/ 68 Int. Cl. B04b 3/02 US. Cl. 210-376 3 Claims ABSTRACT OF THE DISCLOSURE In a pusher centrifuge for material to be centrifuged, having two or more centrifuging drums through which said material being centrifuged passes successively, a member for feeding said material to be centrifuged to the inlet side of the-in the direction of the passing material-first of said drums, and for each of said drums a push member associated with the inlet side of the drum, the improvement that there is provided for at least one further of said drums another feed member supplying material to be centrifuged to the inlet side of said further drum.

BACKGROUND OF THE INVENTION In known pusher centrifuges, the material being centrifuged is transported through the drums in that for each centrifuging drum there is provided a push member which is arranged at its inlet side. This push member moves to and fro in the axial direction of the drum over a fraction of the drum length, whereby the material being centrifuged is moved forwards stepwise on the centrifuging drum. In the' case of telescopically arranged centrifuging drums (US. patent specification 2,755,934) the end of one centrifuging drum is used as a push member for the next centrifuging drum in succession.

The quantity of material which can be transported through the pusher centrifuge is dependent on the diameter of the first centrifuging drum and the height of the material layer formed thereon and also by the stroke of the pushing mechanism and the number of strokes thereof per unit of time.

Since, for various reasons, the speed of advance of the layer of the material being centrifuged on the centrifuging drum is somewhat lower than the speed of the pushing movement of the push member, the gap between the layer of material situated on the drum and the retreating push member increases from drum to drum. The result is that the filter surface of the centrifuging drum is not fully used.

In order to take the first fact into account, in one known pusher centrifuge (German patent specification 1,089,687) decreasing strokes are used for the push members from drum to drum. In this way it is in fact possible to keep the gaps between the material lying on the centrifuging drum and the retreating push member equal for all the drums, but better utilisation of the available filter surface is not achieved.

SUMMARY OF THE INVENTION The invention has as its object to permit better utilisation of the second and following centrifuging drums. In a pusher centrifuge of the type initially described, this problem is solved according to the invention in that in addition to the feed member for the first centrifuging drum there is provided for at least one further centrifuging drum a feed member which conducts fresh material to be centrifuged to the inlet side of said further drum.

In this way, on the one hand the gap produced on the drum when the push member retreats is filled, and on the 3,585,132 Patented June 15, 1971 other hand the quantity of material passing through the pusher centrifuge is increased by the quantity of fresh material fed to the further drum or drums.

Expediently, a control device is provided which controls the times and/or quantities involved in feeding the fresh material to be centrifuged to the individual drums. The aforesaid gaps can be compensated as they occur if the time period for the feeding of fresh material coincides at least for the greater part with the time period wherein the push member arranged at the inlet side of the relevant centrifuging drum moves backwards in the direction of the passing material being centrifuged.

BRIEF DESCRIPTION THE DRAWING One example of embodiment of the subject of the invention is illustrated in simplified manner in the drawing. The single figure shows a vertical axial section through the working side of a pusher centrifuge.

DESCRIPTION OF THE PREFERRED EMBODIMENT In a stator 1 (only partly shown) of the illustrated pusher centrifuge, two telescopically arranged centrifuging drums 2 and 3 are mounted by means of a shaft 4 and a hollow shaft 5 surrounding the latter. Provided at the inlet side of the centrifuging drum 2 is a push member 6 which is connected by means of a push wall 7 and webs 8 to the hollow shaft 5. The end of the centrifuging drum 2 comprises a push member 9 for the centrifuging drum 3 connected to the hollow shaft 5. The push member 9 is connected to the shaft 4 by means of the centrifuging drum 2 and its end wall 10. Provided in the wall 10 are apertures for the passage of the webs 8.

By means of an adjusting motor (not shown), the shaft 4 is moved axially to and fro relatively to the hollow shaft 5 so that the push members 6, 9 are moved axially to and fro relatively to their centrifuging drums 2 and 3 respectively. The fresh material to be centrifuged is brought to the inlet side of the centrifuging drum 2 by means of a conduit 11 and an inlet funnel 13- connected to the push wall 7 by webs 12, and flows successively through the centrifuging drums 2 and 3 under the action of the push members 6, 9. The centrifuge-dried solid material issues at the end of the centrifuging drum 3 into a solids collecting chamber 14. The liquid centrifuged out passes through screening apertures 15 in the centrifuging drums 2 and 3 into liquid collecting chambers 16.

In addition to the inlet funnel 13 which serves as a feed member for the first centrifuging drum 2 there is also provided for the other centrifuging drum 3 a feed member which conducts fresh material for centrifuging to its inlet side, namely an inlet funnel 17. This is secured by means of webs 18 to the inlet funnel 13.

The conduit 11 for introducing fresh material to be centrifuged is provided with a flexible portion 19. The end 20 of the conduit 11, following this portion 19 extends into the openings of the inlet funnels 13 and 17 and is mounted to be displaceable in the axial direction of the centrifuging drums in an end wall 21 of the centrifuge housing. Moreover, a motor actuator 22 connected to the end wall '21 is provided which has a piston 23 connected securely to the end 20 by means of a rod 24.

The pusher centrifuge illustrated operates as follows:

In the position shown in the drawing, the fresh material to be centrifuged arriving through the conduit 11 flows through the inlet funnel 13 to the inlet side of the drum 2. The drum 2' moves towards the right in the drawing, i.e. the push member 6 is moved backwards relatively to the drum 2 and the motor actuator 22 holds the outlet aperture 25 of the end 20 in the position projecting into the inlet funnel 13. As soon as the drum 2 and with it the push member 9' move towards the left in the drawing, ie the push member 9 retreats relatively to its drum 3, the motor actuator 22 draws the outlet aperture 25 out of the inlet funnel 13 into the interior of the inlet funnel 17.

The motor actuator 22 can be connected to the motor actuator (not shown) which is provided for the displacement of the shaft 4 relatively to the hollow shaft 5, so that the control device for the movement of the push members 6, 9 serves as control device for the feeding of the fresh material to be centrifuged to the drums 2, 3. Since the forces for displacement of the end 20 of the conduit 11 are substantially smaller than the forces for the displacement of the shafts 4 and 5 relatively to one another, the movement of the end 20 will lead relatively to the movement between the particular push member and centrifuging drum. In this way the time period for the feeding of the fresh material 'for centrifuging into the particular drum coincides substantially with the time period at which the push member 6 or 9 retreats relatively to the centrifuging drum 2 or 3 respectively. If a separate control device is provided for the motor actuator 22, the feeding of the fresh material may also be initiated already before the retreat movement of the push member begins.

I claim:

1. In pusher centrifuge, for material to be centrifuged, of the type including a first drum and at least one other drum coaxial with the first drum, centrifuged material passing through the first drum and said other drum in succession, a plurality of pusher means, one reciprocable relatively to each drum, an inlet and guide means for guiding material to be centrifuged directly from said inlet to the inlet side of the first drum the improvement which comprises a second guide means to guide material to be centrifuged directly from said inlet to the inlet side of said other drum and means to render said second guide member effective to receive material to be centrifuged from the inlet during at least a portion of the idle stroke of the pusher means associated with said other drum.

'2. The centrifuge defined in claim 1 in which push stroke of the pusher means associated with said other drum occurs during the idle stroke of the pusher means associated with the preceding drum.

3. The centrifuge defined in claim 1 and means to vary said portion of the idle stroke of the pusher means during which the second guide means is effective.

References Cited UNITED STATES PATENTS 3,409,137 11/1968 Schneider 2l0376X JAMES L. DECESARE, Primary Examiner 

